1. Field of the Invention
The present invention relates to video signal processing, and more particularly, to demultiplexing video signals.
2. Background of Invention
Television systems have become increasingly complex as consumers continue to demand greater functionality and performance from television sets. Furthermore, the geographic diversity and business interests of manufacturers and service providers within the television and recording industries has lead to a plethora of analog and digital video formats. For example, analog video signal formats include National TV System Committee (NTSC), Phase Alternation Line Rate (PAL), and Sequential Couleur Avec Memoire (SECAM) television signals. Example digital video signal formats include ITU-R-656 and Digital Video Interface (DVI).
When program channels are transmitted to customer premise devices, such as a television or cable set top box, data packets for program channels are typically multiplexed together into a video data stream. So, for example, program channels, such as CNN, HBO, and ESPN can be combined into a single data stream. When the video data stream is received by a customer premise device, the customer premise device must be able to discern which packets belong to the program channel of interest (i.e., what channel is to be viewed or recorded).
A common way to identify packets within a video data stream that are associated with a particular program channel uses program identification (PID) information. This approach can be referred to as a PID parsing approach. In this approach, each packet within a video data stream contains a PID that contains information that tells a customer premise device which channel a particular packet of information is associated with.
In another approach, data packets within a video data stream that are associated with a particular program are allocated within particular time slots of a data frame. With this approach a distribution device, such as a cable system headend, organizes data packets into frames with packets for a particular program channel located in specific time slots within the frames. This approach can be referred to as a time division multiplexing approach. An example of this approach is transport stream multiplexing format (TSMF), which has been recently developed by a consortia of television manufacturers for use in Japan. Within this approach it is also common that packets will contain a PID.
What is needed is a system and method for efficiently demultiplexing video signals that use both a PID and are multiplexed using a time division multiplexing approach.